Dry-kiln.



H. l). TIEMANN.

DRY KILN.

APPLICATION FILED FEB. 20. I9I'7.

lartented June 4, 1918.

2 SHEETSSHEET 2- IWT /l /l/l IINI HARRY DONLD TIEMANN, OF MADISON,WISCQNSIN.

nav-Kinn.

'Specication of Letters Patent.

Patenten aan@ a, raie.

Application led February 20, 1917. Serial No. 149.972.

To all whom t may concern:

Be it known that I, HARRY DONALD Tm- MANN, a citizen of the UnitedStates of America', and an employee of the Department of Agriculture ofthe said United States, residing at Madison, in the county of Dane,State of Wisconsin, (whose postoliice address is Madison, Wisconsin,)have invented a new and useful Improvement in Dry-Kilns.

This application is made under the act of March 3, 1883,@11. 143 (22Stat., 625), and

the invention herein described and claimed,

may be used by the Government ofv the United States, or any ofitsoiicers or employees, in the prosecution of work for the Governmentor any person in the United States, without payment to me of any royaltythereon.

My invention relates to kilns for drying lumber or other articles.

The object ofmy invention is to provide an improvement in a kiln fordrying flat piled lumber by means of superheated steaml at atmosphericpressure.

The features of my invention are:

(l) An arrangement of parts so that the principle of a high circulationof steam through the lumber at a low degree of suerheat may be utilizedwith flat piled lumer, thus doing away with the necessity' of specialforms of truck necessary for edged stackin as have been used heretofore.

.(2) n arrangement for reversing the direction of the circulationcurrent by simply closing and openin valves, and

(3) Means where y the superheat of the steam as it passes through thelumber isl pre` vented from Vdroppin to the saturation point, said meansconslsting of a reheating coil of pipes placed between the piles andlumber.

The object, characteristic features, and scope of my invention will bemore readily understood from the following description taken inconnection with the accompanying drawings wherein:

Fi re lis a vertical sectional view across the kiln showing two fiatpiles of lumber.

Fig.- 2 is a vertical section through the kiln longitudinally in theplane, M N,

Fig. 1.

eferring to the drawings, the drying chamber is designated, a,containing two flat piles of lumber, as shown at A, the boards(DEDICATED T0 THE PUBLIC.)

running in a direction perpendicular to the plane of the paper. Thelumber is piled in the ordinary manner upon simple bunks, b, which runupon rails, K.' Immediately beneath the rails, K, isa solid horizontallyplaced shield, D, with vertically projecting ends, E. Suspended from theroof of the chamber a, is'a similar shield, B, having verticallyprojecting ends, C. These shields, B and D, form two narrow fiues, G andJ, within the kiln chamber, a, in which are placed the steam jets, forforcing the circulation. These jets are formed by erforating Va highpressure steam pipe with small holes about 33E to it, of an inch indiameter and spaced every 12 or 18 inches. The steam jet pipes are shownin four pairs placed at F, F', F and F Each pair consists of twoseparate pipes,P d and d', with their respective perforations facing inopposite directions in a horizontal plane. The pipes d and d arecontrolled by independent valves c and e', so that the direction of thesteam jets may be directed either to the right or to the left at will byclosing and opening the respective valves, e and e thus reversing thedirection of the circulation. While I have shown two pairs of steampipes in each of the passageways, G and J, a single pair may sometimesanswer the purpose or more than two ma be used, the plurality of thesepipes not a ecting the principle of my invention. H represents highpressure steam pipes placed near either side wall of the kiln for thepurpose of superheatin the steam. H is a coil of steam pipes placebetween the two loads of lumer for the purpose of reheating the steamduring its passage owing to its rapid loss of heat by4 contact with thelumber. The direction of the currents of vapor is indicated by thearrows, asproduced by one set of steam jets, d. When the other set ofjets, d',

is brought into operation, and the first set, d, is turned oil", thecirculation will be in the opposite direction. The end projections, Cand E, of the two shields, B and D, respectively', are for the purposeof preventing eddy currents'and directing the vapor uniforml throu h alllayers of the pile of lumber. It has baiiles, C and E, a swirling orvortex motion of the vapor occurs near the two ends of the pile whichmay cause the motion through the lumber to be reversed at these eenfound that wlthout these points. Lris a tight fitting door closing the'front of the kiln and, P, is a vent to the outer atmosphere with` a'through the piles check valve, h, opening outwardly, for the escape ofexcess vapor. In practising my invention, the cold wet lumber is firstrun into the kiln and the doors, L, are tightly closed.

The steam jets, d, for example, facing one way are then turned on fullwith steam pressure of 2O to 6() pounds gage which causes a rapidcirculation of saturated steam e cut down until aconstant temperature isse-v gi'ns to pass oif rapidly cured. ,As the temperature of the wetlumber gradually rises to 212, the water vbeby. boiling, and at thispoint the excess pressure produced by the steam from the steam jets, d,and the vapor from the lumber, forces the excess out through the vent,P, or through any leakages in the kiln. When this operation hascontinued until that portion of the piles nearest the pinging vapor hasbecome sufficiently d the length of time, depending upon the kind,thickness,` and moisture condition of the lumber, the first steam jets,d, are turned oif and the jets, d', facing the opposite way are turnedon, thus reversing the entire circulation, and bringing about a rapiddrying of the opposite sides of the piles. This condition is held untilthe lumber has reached the desired degree of dryness, or the circulatiormay be reversed a number of times during the drying. The reversal of thecirculation enables considerably wider piles to be used than is possiblewhere the circ lation is all in the one direction.

The evaporating capacity of superheated steam is proportional to theproduct of the weight of steam coming in contact with the lumber timesthe number of degrees -it is heated above the boiling point. Therefore,by greatly increasin l the velocity of the steam passing throng thelumber, its temperature may be correspondingly reduced without losingany of its drying capacity. One objection to the use of superheatedsteam for drying lumber is the rapidity with which it parts with itsheat and is reduced to the saturated condition where it can produce nomore drying. With slow circulaas shown by the arrows.` very rapidly andwets y `rection, heating pipes 'the-.boiling point, and a vent 'theiioor and near the ceiling of tion` this 'causes the portion of thepiles lof* lumber with which the steam first comes in contact to dryvery rapidly while the far side of the piles dries very little or not'at all. Byforcing a rapid circulation, keeping the piles very narrow,not over four feet in width, and reheating the vapor as it passes fromone pile to the next and, by reversing the circulation during the dryingoperations so that the damp sides of the piles may in turn receive thedirect heat from the impinging steam, the difficultypracticallydisappears.

The use of superheated steam has been found practicable with manysoftwoods or conifers, but is not applicable to most of the hardwoodsowing to the injurious effect of the high temperature in many of thelatter species.

From the foregoing, it is thought that the construction, operation andmany advantages of the herein described invention will be apparent tothose skilled in the art, without further description, and it will beunderstood that various changes in the size, shape, proportion, andminor details of construction may be resorted to without departing fromthe spirit or sacrificing any of the advantages of the invention. Y

Having thus described my-finvention, f claim:

1. In a dry kiln for receiving piles of fiat piled lumber, shields aboveand below the piles forming passageways, steam jets in these passagewaysfor forcing the circulation, heating pipes near the side walls of thekiln, heating pipes between the piles of lumber, and a vent for escapeof excess vapor. v

2. In a dry kiln for receiving piles of flat piled lumber; shields aboveand below the piles forming passageways, steam jets in these passagewaysfor forcing the circulation in one direction; other steam jets in thesame passageways for forcing the circulation in the opposite direction,heating pipes placed near the side walls, and a vent for the escape ofexcess vapor.

3. In a dry kiln, shields placed near the ceiling and near the floorforming passageways, steam jets in these passageways for forcing thecirculation in one direction, other steam jets in said passageways forforcing the circulation in the opposite diplaced'in the current of vaporfor superheati'- g the same above for the escape of excess va or.

4. In a c amber for drying lumber or other moisture bearing material,shields near said chamber forming passageways, steam jets in thesepassageways for forcing the circulation in one direction, other steamjets in said passageways -for forcing the 'circulation in lthe oppositedirection, heating pipes in the current of vapor for superheating thesame above the boiling point, and a vent for the escape of excess vapor.

5L In a dry kiln for receiving piles of Hat piled lumber in said kiln,trucks to hold said piles of lumber, rails upon which the trucks arerolled, a movable door in the front of the kiln, a shield beneath thepiles of lumber forming a passageway between the shield and the floor,another shield above the piles of lumber forming a passageway betweenthe shield and the roof, bame plates attached to the ends of theshields, steam jets in said passageways for forcing the circulation inone direction and other steam jets in said passageways for forcing thecirculationv in the reverse direction, heating pipes near the side wallsof the kiln in the current of vapor, heating pipes between the piles oflumber, and a vent for the escape of excess vapor. l

In testimony whereof, I alix my signature in the presence of twosubscribing witnesses.

HARRY DONALD TIEMANN.

Witnesses:

ALFRED W. DoHR, CHAs. P. JUCKEM.

